This invention relates to earth boring drill bits and, more specifically, to rotary cone cutters for drilling wells and blast holes.
Rotary cone cutters are constructed having multiple rolling cutters on one end that rotate cooperating with one another to reduce earth and hard rock formations. The individual rolling cutters are mounted on multiple leg means that extend from, and are permanently attached to, the body of the drill bit.
In the manufacture of the drill bits, rolling cutters are mounted on the legs of the drill bit, usually using factory methods and tools. The legs that carry the rolling cutters are then assembled at the manufacturing plant, usually with the aid of a special locating fixture, and permanently welded one to the other and threaded.
The drill bits, when used in the field, are subject to extreme conditions of dirt, dust, shock and vibration such that uneven wear or breakage can occur on the multiple rolling cutters. In many instances, one of the rolling cutters of the drill bit may wear out or break in a short period of time, while the other cutters remain in working condition.
Because each of the multiple cutters must cooperate when drilling, the entire drill assembly becomes ineffective when one of its multiple cutters breaks or becomes worn beyond a certain point.